Office of Compensation Analysis and Support 

Program Evaluation Plan

Document Number: 

OCAS-PEP-008 

Effective Date: 12/7/06 

Revision No. 0

Modification of NIOSH-IREP lung cancer risk model: impact of 

“combined” lung model on non-compensable lung cancer claims Page 1 of 5 

Author: ______Signature on File Date: 12/07/2006 Russell W. Henshaw, Epidemiologist 

Approval: ______Signature on File Date: 12/07/2006 J.W. Neton, Associate Director for Science 

Supersedes: None 

ISSUE 

AUTHORIZATION 

DATE 

EFFECTIVE 

DATE 

REV. 

NO. DESCRIPTION 

12/7/06 12/7/06 0 

New document to evaluate the modification 

of the NIOSH-IREP lung cancer model on 

previously competed cases 

1.0 Description

The NIOSH-IREP lung cancer risk model, labeled “Lung (162)” in NIOSH-IREP, calculates the 

probability of causation (PC) for cancers of the lung, trachea, or bronchus. NIOSH modified this 

risk model on February 28, 2006 via the implementation of NIOSH-IREP Version 5.5. Version 

5.5 and Version 5.5.1, which superseded v5.5 on May 16, 2006, are programmed with a 

“combined” lung cancer risk model. The combined model consists of two alternative lung risk 

models: the lung model used in NIOSH-IREP v5.4 and earlier versions, plus the lung model used 

in NIH-IREP, a separate IREP software program maintained by the National Cancer Institute 

(NCI). NCI revised the NIH-IREP lung model in 2003 based on updated analyses (1, 2) of 

Japanese atomic bomb survivor cohort data, including the application of new assumptions about 

the interaction between cigarette smoking and lung cancer. (The revised NIH-IREP lung model 

is the model that was added to NIOSH-IREP.) For each cancer of the lung, trachea, or bronchus, 

NIOSH-IREP now calculates separately the PC value produced by each of the two different lung 

cancer risk models and reports the higher PC at the upper 99th percentile credibility limit as the 

PC value of record for the claim. 

In the revised NIH lung cancer model, risk is adjusted for age at exposure and age at diagnosis. 

The NIOSH lung model does not adjust for these age-dependent factors. Further, the NIH lung 

model relies less on a multiplicative interaction than the NIOSH model in accounting for the 

interaction between cigarette smoking and lung cancer. Consequently, the same claim inputs can 
Effective Date: 12/07/06 Revision No. 0 Document No. 

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produce different PC values for some exposure profiles for claimants with lung cancer. The NIH 

lung model is generally more favorable to smokers than the NIOSH lung model, whereas the 

NIOSH lung model is generally more favorable to non-smokers than the NIH lung model. Other 

potential effects on PC (age and gender-related, for example) vary according to the 

circumstances of each case and are more difficult to predict. (3) 

NIOSH-IREP v5.5 and v5.5.1 also incorporate a bias correction factor for random errors in 

dosimetry for “never smokers” who were exposed to radon. Due to a programming oversight, 

this correction had been omitted for “never smokers” and was applied only to smokers in earlier 

versions of NIOSH-IREP. NIOSH-IREP v5.5 corrected this error. 

The risk model modifications described above can result in no lower PC value for the same set of 

claim inputs than had been calculated under previous versions of NIOSH-IREP (versions 5.4 and 

earlier). This change was adopted based, in part, on recommendations from outside experts and 

was endorsed by the Advisory Board on Radiation and Worker Health (ABRWH). Again, the 

modifications pertain only to the “Lung (162)” risk model and apply only to cancers of the lung, 

trachea, or bronchus. 

2.0 Preliminary Issue Evaluation

In accordance with the lung cancer risk model changes described above, non-compensable lung 

cancer claims completed under older versions of NIOSH-IREP were eligible for evaluation. 

Since the potential effect on PC values for individual lung cancer claims was not fully 

predictable, the decision was made to evaluate all previously non-compensable lung cancer 

claims completed under NIOSH-IREP versions 5.4 and earlier (versions in operation prior to 

February 28, 2006, the date the combined lung cancer risk model was first implemented). The 

ORAU team researched the NIOSH/OCAS claims database and identified 920 such noncompensable claims (PC<50% at the upper 99th percentile credibility limit). For claims that had 

been reworked due to DOL returns, only the most recent revision of each such claim was 

considered. 

This preliminary evaluation consisted of running each of the 920 identified claims in NIOSHIREP v5.5.1, which includes the “combined lung model” first introduced on 2/28/06, to 

determine the effect on PC outcomes. Of the 920 claims, 729 were “single cancer” claims. That 

is, only one cancer (primary or secondary) was reported for each claim and the applicable 

NIOSH-IREP risk model was “Lung (162).” The remaining 191 claims were “multiple cancer” 

claims, in which two or more cancers (primary and/or secondary) were reported for each claim 

and the “Lung (162)” model was used for at least one of the cancers. 

As displayed in Table 1, this preliminary evaluation revealed a PC increase for 95 of the 920 

identified claims. As would be expected, the alternative NIH lung cancer risk model produced 

the higher PC value for the vast majority (91, or 95.8%) of the 95 affected claims. Of these 91 
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claims, 70 were single cancer claims and 21 were multiple cancer claims. However, the 21 

multiple cancer claims included 28 separate lung cancers. Thus, the total number of lung cancers 

among all claims for which the NIH lung model produced a higher PC (versus the NIOSH lung 

model) was 98. The mean and median increase in PC produced by the NIH lung model versus 

the NIOSH model for the 98 lung cancers was 1.87 and 1.30 percentage points, respectively 

(range = 0.02 to12.58 percentage points). The NIH lung model produced a lower PC value at the 

upper 99th percentile credibility limit than the NIOSH lung model for 829 (90.1%) of the 920 

previously non-compensable claims. 

Of the 95 claims with increased PC values, there were only 4 claims in which the NIOSH v5.51 

lung model produced a higher PC than the NIOSH lung model used in earlier versions of 

NIOSH-IREP (v5.4 and earlier). Because the smoking history associated with each of these 4 

claims was “Never Smoked” and because each claim included radon exposure, the PC increases 

can be attributed to the bias correction factor for random errors in dosimetry for non-smokers 

exposed to radon (see Section 1.0). The PC increases due to the bias correction factor for the 4 

affected claims were 1.01, 5.23, 5.29, and 6.47 percentage points (mean increase = 4.50; median 

= 5.26). 

PC values at the upper 99th percentile credibility limit showed an increase in 73 (10.0%) of the 

729 “single cancer” claims and in 22 (11.5%) of the 191 “multiple cancer” claims for, as noted 

above, a total of 95 (10.3%) of the 920 identified lung claims. The new PC values for 84 

(88.4%) of the 95 claims remained below 45% and require no further evaluation. However, 11 

(11.6%) of the 95 claims had a new PC value of 45% or higher and will require further review. 

Each of the 11 claims with a new PC ≥45% will require a rework and/or 30 IREP runs at 10,000 

iterations to establish the average (arithmetic mean) PC value. Since 4 of these 11 claims have 

more than one cancer, 30 IREP runs will be required for each cancer (i.e., including cancers 

other than lung) for each of the 4 claims. 

Table 1: Effect of NIOSH-IREP v5.5x “combined” lung cancer risk model on probability of 

causation (PC) values at the upper 99th percentile credibility limit (results of preliminary 

evaluation of all non-compensable lung cancer claims originally completed under NIOSHIREP versions 5.4 and earlier) 

Type of 

Claim 

Number 

of Claims 

No PC 

Increase 

PC 

Increase 

Increase 

Due to 

NIH 

Lung 

Model 

Increase 

Due to Bias 

Correction 

Factor 

New 

PC 

<45% 

New PC

= 45 - 

49.99% 

New 

PC 

≥

50%

Single 

cancer 

729 656 73 70 3 66 3 4

Multiple 

cancers 

191 169 22 21 1 18 4 0

Totals 920 825 95 91 4 84 7 4
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3.0 Plan for Resolution or Corrective Action

Of the 920 lung cancer claims identified for this preliminary evaluation, the “combined” lung 

cancer risk model used in NIOSH-IREP v5.5.1 produced no PC increase in 825 claims. Of the 

95 claims with an increased PC value at the upper 99th percentile credibility limit, the new PC for 

84 of the 95 claims remained below 45% and will require no further evaluation. Thus, the 

evaluation is considered complete for a total of 909 (825 + 84) of the 920 evaluated claims. 

For the remaining 11 claims in which the new PC increased to 45% or higher, further evaluation 

is necessary. Each of the 11 claims (7 “single cancer” claims and 4 “multiple cancer” claims) 

will be subjected to 30 IREP runs for each cancer to determine the arithmetic mean PC value for 

each claim. For the 4 “multiple cancer” claims, 30 runs will be performed for each cancer, both 

lung and non-lung, in order to establish arithmetic mean PC values for use in the multiple 

primary cancer equation. DOL will be notified of each claim for which a rework is needed. 

After the evaluation has been finalized, a Program Evaluation Report (PER) will be issueda

 and 

an itemized list of claims will be provided to DOL that will display claim-specific evaluation 

results. 

Finally, upon completion of the PER, a notation will be added to the administrative record of 

each of the 920 evaluated claims indicating that the claim has been evaluated and reporting the 

effect, if any, upon PC as a result of the new combined lung model. Each notation will include 

the following form, appropriately annotated relevant to the effect on the claim: 

NIOSH has determined that the application of the PER referenced above to this dose 

reconstruction would be to: 

 Increase the probability of causation at the 99th percentile from <50% to ≥50%, therefore 

the claim has been reworked. 

 Increase the probability of causation at the 99th percentile, but the resulting probability of 

causation would still be <50%, therefore no change is warranted at this time. Should this 

dose reconstruction be re-opened in the future, this change will be applied. 

 Decrease the probability of causation at the 99th percentile. Since this dose 

reconstruction currently has a probability of causation less than 50%, no change is 

 

a

 In accordance with PR-008, Preparation of Program Evaluation Reports and Program Evaluation Plans, the final 

evaluation will be issued as a Program Evaluation Report (PER). The PER will include the information contained in 

this PEP and the results of the final analysis of all cases that were evaluated. 
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warranted at this time. Should this dose reconstruction be re-opened in the future, this 

change will be applied. 

4.0 References

1) Pierce DA, Sharp GB, Mabuchi K: Joint effects of radiation and smoking on lung 

cancer risk among atomic bomb survivors. Radiation Research 159: 511-520, 2003. 

2) Land CE and Pierce DA. Likelihood profile for parameter alpha used in computation of 

statistical uncertainty for ERR/Sv in NIH-IREP lung cancer model. Personal 

communication from Charles Land (NIH/NCI) to NIOSH, February 3, 2004. 

3) Apostoaei AI and Trabalka JR, SENES Oak Ridge, Inc. Differences in the estimation of 

lung cancer risk between NIOSH-IREP and NIH-IREP. September 20, 2004.